1. Field of the Invention
The present invention relates to an optical signal demultiplexing device that multiply demultiplexes an optical signal multiplexed by an optical time-division system.
2. Description of the Related Art
In recent years, in an optical fiber communication system, OTDM (Optical Time Division Multiplex) for time-division multiplexing optical signals directly in the state of light is being studied. According to this OTDM, when multiplexing optical signals, the optical signals are multiplexed at a timing assigned beforehand. When demultiplexing the multiplexed optical signal, multiplexed light is demultiplexed at a timing assigned beforehand. By multiplexing and demultiplexing the optical signals directly in the state of light by using the OTDM, a large capacitance of an efficient and economic network can be achieved.
Japanese Patent Application Laid-open No. H7-221708 discloses a technique of compensating for a delay of an optical signal generated by an optical path difference within a node, using dispersion dependency of an optical fiber on a wavelength, when the optical signal passes within each node that constitutes an optical fiber communication system, thereby achieving a precise synchronization of the optical signal concerning the optical fiber communication system.
However, according to the conventional technique described above, because the optical signal of each channel needs to be multiplexed and demultiplexed at a specified timing in the OTDM, there has been a problem in that high-level process cannot be performed in the state of the optical signal (for example, according to the conventional technique, only a path change can be performed in the state of the optical signal).
To progress the use of light in the network, the cost of processing an optical signal directly in the state of light needs to be lower than the cost of converting an optical signal into an electric signal. At the same time, the process of the optical signal in the state of light needs to be diverse like the process of the electric signal. That is, in processing light directly in the state of light, when only the path can be changed, it is considered unlikely that the use of optical signals in the network becomes popular by replacing the electric signals that can be flexibly processed.
In other words, when the optical signal is processed directly in the state of light, it is considerably important that light can achieve high-level process that the electric signal can achieve.